With the development of Ethernet towards a multi-service bearer, particularly the increasing requirements of some services on the reliability and real-time property of a network, the Ethernet widely adopts a ring network to improve the reliability of the network. In addition, in the protection solution for a ring network, it is generally required that fast protection switching can be completed within 50 ms. At present, the technology for fast protection switching can be implemented based on the G.8032 protocol of the International Telecommunication Union (ITU-T).
Based on the G.8032 protocol, an automatic protection switching protocol and mechanism is defined for an Ether layer of a ring topological Ethernet. A network protection method is adapted to the ring topological Ethernet, and implemented by such a flow: a link is selected as a ring protection link in a ring topological Ethernet; one node adjacent to the ring protection link, which is called a node to which the ring protection link belongs, controls the blocking or opening of the ring protection link, and a port at the node to which the ring protection link belongs, which is adjacent to the ring protection link, is called a port adjacent to the ring protection link. When all the links of the Ethernet ring network are normal, at least one of two nodes adjacent to the ring protection link blocks a port connected with the ring protection link to prevent protected data from passing through the ring protection link, in this way, there is only one communication path between any two nodes in the Ethernet ring network, so never a closed communication path exists in the Ethernet ring network, thus a closed loop and a network storm are prevented; when a link in the Ethernet ring network has a failure, if the failed link is not the ring protection link, then the nodes at the ports adjacent to the ring protection link are blocked and the blocked ports on the ring protection link are opened, so that protected data can pass through the ring protection link, a new communication path is generated between any two nodes on the ring protection link, the re-connection of the communication path is guaranteed and the reliability of the network improved.
In the switching process of an Ethernet ring network, a communication path of a data flow needs a change, since information in an address table recorded by each node may be not available any longer after the communication path of the data flow is changed, each node may need to update the address table, specifically, deleting address items of ports of a ring. In the G.8032 protocol, when a node sends an Ethernet ring network protection protocol frame, the protocol frame includes a node number of the node and an index number of a blocked port; after other nodes receive the protocol frame, the node number and the index number of the blocked port in the protocol frame are extracted and compared with those of updating record information which is originally stored and corresponding to a receiving port; if they are different, the updating record information corresponding to the receiving port is updated with the extracted node number and the index number of the blocked port; and if the node number and the index number of the blocked port in the protocol frame are different from those of updating record information corresponding to the opposite end port of the receiving port, the node may further need to update the address table.
Although such solution for updating an address table in an Ethernet ring network guarantees that error address items can be fast deleted during switching in the Ethernet ring network, the problem of repeated updating during the switching is also caused. For example, in the scenarios of switchback after link failure restoration, link unidirectional failure, manual switch protection switching request, forced switch protection switching request and other such local protection switching requests, if a node sends an Ethernet ring network protection protocol frame and has updated the address table of its own when making a local protection switching request, then, after the node receives the Ethernet ring network protection protocol frame sent by itself, the node repeatedly updates the address table once more because original node number and index number of a blocked port in updating record information of a port are not consistent with the information contained in the received protocol frame. At present, there is still no effective solution for how to prevent repeated updating of an address table in Ethernet ring network protection.